Add a tool to dump git SHAs of API changes

Necessary for use by API council near the end of a release to verify
their server-side tool has filed bugs for all the API changes.

This utilized bazel-query to figure out what contributes to current.txt,
and then finds api subdirectories in the relevant directories. Finally,
it prints the non-merge SHAs of changes in those directories.

Test: frameworks/base/api/dump_api_shas.sh
Change-Id: I330bfe24fb4df5a8a9218241540f7a7ab3b66e2f
diff --git a/api/dump_api_shas.sh b/api/dump_api_shas.sh
new file mode 100755
index 0000000..c023b31
--- /dev/null
+++ b/api/dump_api_shas.sh
@@ -0,0 +1,56 @@
+#!/bin/bash -e
+# This script dumps the git SHAs of all commits inside api tracking directories.
+# It can used by tools wanting to track API changes, and the primary original
+# purpose is to verify verify all API change SHAs have been tracked by the
+# server-side API-council tools.
+#
+# The only argument is used to specify a git commit range to filter by.
+#
+# Example invocation (API changes between O and P):
+# frameworks/base/api/dump_api_shas.sh origin/oreo-dev..origin/pie-dev
+
+set -o pipefail
+
+eecho() { echo $@ >&2 ; }
+
+if [[ $1 == *..* ]]; then
+    exclude=${1/..*}
+    include=${1/*..}
+else
+    eecho No range or invalid range specified, defaulting to all commits from HEAD.
+    exclude=
+    include=HEAD
+fi
+
+eecho -n building queryview...
+{ source build/envsetup.sh && lunch aosp_arm && m queryview; } >/dev/null 2>&1 \
+  || { eecho failed; exit 1; }
+eecho "done"
+
+# This finds the directories where the dependant java_sdk_libs are defined
+bpdirs=$(
+  bazel query --config=queryview --output=package \
+    'kind(java_sdk_library, deps(//frameworks/base/api/..., 1))' 2>/dev/null
+  echo frameworks/base/core/api # Not a java_sdk_library.
+  echo frameworks/base/services/api # Not a java_sdk_library.
+)
+
+# Find relevant api subdirectories
+apidirs=$(
+  find $bpdirs -type f -name '*current.txt' -path '*/api/*' \
+    | xargs realpath --relative-to=$(pwd) | xargs dirname | sort | uniq
+)
+
+# Dump sorted SHAs of commits in these directories
+{ for d in $apidirs; do
+    ( cd $d
+      eecho inspecting $d
+      exclude_arg=$(test -n "$exclude" && {
+        git rev-parse -q --verify $exclude > /dev/null && echo "--not $exclude" \
+          || eecho "$d has no revision $exclude, including all commits"; } || true)
+      for f in $(find . -name '*current.txt'); do
+        git --no-pager log --pretty=format:%H --no-merges --follow $include $exclude_arg -- $f
+        echo # No trailing newline with --no-pager
+      done
+    )
+done; } | sort | uniq